Addition and Subtraction Fact Families Background Information for Teachers and Caregivers
This page contains information to support educators and families in teaching grade K-3 students about addition and subtraction fact families. It is designed to complement the Addition and Subtraction Fact Families topic on BrainPOP Jr.
Identifying fact families is an important skill that prepares children to use number relationships throughout their math education. What are fact families? A fact family is a group of related math facts that have the same numbers. Inform children that when they look closely at a fact family, they will notice patterns. Understanding these patterns makes math easier.
Share an example, such as 2, 3, and 5. Show how 3 + 2 = 5 and 2 + 3 = 5. Also illustrate how 5 – 2 = 3 and 5 – 3 = 2. The three numbers (2, 3 and 5) make up a fact family. Point out that the order you add numbers doesn’t matter. Explain to your child that an operation is a way to solve a math problem. Addition and subtraction are both operations. Point out that fact families always have the following:
- three numbers (e.g., 2, 3, 5)
- four math facts (e.g., 2 + 3 = 5; 3 + 2 = 5; 5 – 3 = 2; 5 – 2 = 3)
- two operations (addition and subtraction)
Give children some other examples of addition and subtraction fact families. For example, 6 + 2 = 8, and 2 + 6 = 8. Ask children what 8 – 2 equals. If they can’t figure out the answer, point to the third number in this fact family: 6. Remind children that addition and subtraction fact families always have two addition sentences and two subtraction sentences.
Sometimes children may confuse which numbers to add or subtract in a fact family. They may mistakenly add the sum or largest number (in the example above, that would be 8). to one of the smaller numbers (2). This would result in an equation reading 8 + 2 = 10. But this addition sentence is not part of our fact family, which only contains the numbers 2, 6 and 8. To clarify how to use fact families, create a fact family triangle with your child.
Draw a triangle and label bottom points with the smaller numbers from your fact family: 6 and 2. Then label the top point with the largest number: 8. Finally, draw a plus and a minus sign inside the triangle. Show children how they can point from number to number and create a fact-family operation using the plus and minus signs. They should never add numbers to the top number–that’s only for subtracting. A fact family triangle makes it easy to find the four related number sentences in an addition and subtraction fact family.
Inform children that knowing fact families can help them solve math problems. If they know that 8 + 4 = 12, then they also know that 12 – 8 is equal to 4. When working on a math problem, it’s useful to see if a fact family can help them solve it. We recommend that children also watch the Basic Adding and Basic Subtraction movies as a review.
